A paradoxical Tropheryma whipplei western blot differentiates patients with whipple disease from asymptomatic carriers.

BACKGROUND: Tropheryma whipplei is a bacterium that causes Whipple disease. However, T. whipplei can be carried in the gut of asymptomatic people, which may lead to difficulty in the interpretation of positive stool sample test results.

METHODS: This study included 60 patients with classic Whipple disease at the time of diagnosis and 26 T. whipplei carriers. Western blots testing for total immunoglobulin (Ig), IgG, IgM, and IgA were performed using glycosylated and deglycosylated T. whipplei. A blind test involving 10 patients and 10 carriers was performed. Sera samples from 32 treated patients were tested for total immunoglobulin.

RESULTS: Total immunoglobulin from patients with classic Whipple disease exhibited either a lack of reaction (23 [38%] of 60 patients) or a decrease in reaction (33 [55%] of 60 patients) with a T. whipplei glycoprotein of 110 kDa after deglycosylation. Only 4 patients exhibited a stronger immune response than that which was observed for carriers (21 [81%] of 26 carriers). Five carriers presented a response profile similar to that for the patients. IgM (4 [7%] of 60 patients) or IgA (1 [2%] of 60 patients) responses were rarely observed but were exclusive to patients. Overall, results were consistent and reproducible. Antibiotic therapy had no effect on the serological profiles of the patients.

CONCLUSIONS: Western blot serology is useful to distinguish between carriers and patients; paradoxical responses of the antibodies were investigated.